The letter stresses that ticket office purchases have declined sharply in recent years, due to the success of Oyster card, while LU passenger numbers have continued to rise. See the graph below:

Collins writes: "Let me be absolutely clear – safety is at the heart of our vision to transform the Tube and we make the following commitments to all of our customers and staff:

1. There will always be staff present at every station to help customers

2. All stations that currently have a ticket office service will continue to have one

3. There will be no compulsory redundancies

We are proposing to reduce ticket office opening hours because our customers are just not using them as much as they used to. Use of ticket offices is down around 50 per cent on five years ago. Today, only 1 in 20 journeys starts with a visit to the ticket office and this number continues to decline. 80 per cent of all Tube journeys are now made using Oyster.

So we don’t need or want our staff to be stuck behind glass in under used ticket offices; we want them out on our stations where our customers need them – on platforms, in ticket halls and at gate lines."

Bob Crow, RMT leader, is putting safety at the heart of the matter as he knows this will gain more sympathy than purely striking over job cuts and said "We have already warned that the cuts that are being planned by TfL will turn tube stations into a muggers paradise and it now appears that the company are speeding up the process and are already leaving stations unstaffed, or babysat with just one member of staff, without any consultation.

That is a scandalous dereliction of duty and it is only a matter of time now before TfL and Boris Johnson have a tragedy on their hands as a result of their cavalier disregard for public safety."

Collins letter says: "In addition to our ongoing commitment to having staff where customers need them most, there are also more police patrolling the Tube network – 700 officers – than ever before. This helped to reduce crime by eight per cent last year. While one crime is always too many, there are now just 12 crimes per million Tube customer journeys.

We’re also installing more and improved CCTV cameras on stations and trains, to more than 14,000 in years to come, to help us look after you.

All of this must be done in a way that delivers the best possible value for money for Tube customers and taxpayers.

It’s a fact that, like any public service, we have to be as efficient as we can, particularly in the present difficult economic times. It’s true we are reducing the number of staff we have overall; but by putting our staff in the areas they are most needed, we can do this without affecting your journey or compromising your safety."

The full letter will be on TfL's website soon. We'll know by tomorrow whether these efforts and the discussions with unions will be enough to stop the strike threats.